Funny thing happens when I turn off/on anything

Status
Not open for further replies.
N

nhfire77

Senior Member
Location
NH
I don't really know anything about power quality issues so i thought I'd ask.

In my home I have a Standard 120/240 100 Amp service.

When watching TV and the electric dryer kicks on the TV gets a "blip" or a little interference. I am not surprised at this since its the biggest load in the house. Since noticing this, I have also recognized that every load that is made and disconnected also causes this "blip". Every light incandecent and CFL.

The TV did not do this in another house I lived in. Its a two year old LCD TV

Time of day is irrelevant, it occurs at all hours. The voltage is 122-124 all the time.


Why is this?
 
Anything from loose connections to a severely undersized utility transformer. Got a call from a friend of mine complaining of the same thing on a house he had just bought. I went through the panel and checked connections ,they were all good. Pulled the meter all good and tight there. Followed the triplex out to the transformer. There were 10 houses being fed from 1-15KVA 7200 to 120/240 transformer. These were all older houses that more than likely all started out with 60 amp services and all gas appliances. All had been upgraded over the years. Utility engineer came out and put an amp probe on the secondary. It was averaging 250 amps per leg.
 
masterinbama said:
Anything from loose connections to a severely undersized utility transformer. Got a call from a friend of mine complaining of the same thing on a house he had just bought. I went through the panel and checked connections ,they were all good. Pulled the meter all good and tight there. Followed the triplex out to the transformer. There were 10 houses being fed from 1-15KVA 7200 to 120/240 transformer. These were all older houses that more than likely all started out with 60 amp services and all gas appliances. All had been upgraded over the years. Utility engineer came out and put an amp probe on the secondary. It was averaging 250 amps per leg.
Click to expand...

Everything from the service drop to the MDP is tight. The POCO transformer is 75-80 feet from the Point of attachment, of course I cannot tell if its overloaded.

The service was 60 amp before I moved in, it was upgraded 6 months before I bought it to 100 amp.
 
This is not to uncommon, in a romex house, as conduit blocks some of the EFI from switch closure, but you stated it was when you turn a switch off which leads me to believe this is more of a inductive / surge kick back,
did you have the TV plugged into a surge/filter strip at the other house and not at this one.
if you did is it the same one or different brand, kind?
some have better filtering that others.
is these things closer to the TV location that at the other house?

cable / antenna feed ran close to circuit conductors?

there are many things to check.
I had a week neutral that caused this because the TV cable from the cable company is bonded at the pole and the house so it will carry some of the unbalanced neutral current, so this is another area to check, use an clamp on amp meter to see if there is current on the cable coming from the pole, this has to be between the ground bond block at the house and the pole.
 
Last edited:
Set the TV on an aux input, disconnect the cable and see if it still does it. The interference may be coming over the cable and not through the electrical system. Could have a bad ground on the cable system or a bad connection that does not shield the transient during load switching.
 
Status
Not open for further replies.
Top